ConvertAll Methods Implementation for Multidimensional Array in C# - follow-up

Question

This is a follow-up question for ConvertAll Methods Implementation for Multidimensional Array in C#. Thanks to aepot's answer and Olivier's answer. In order to match the usage of the build-in API Array.ConvertAll, the input /output array types of the implemented methods below are similar to [], [,], [,,] and etc. style.

The experimental implementation

The experimental implementation is as below.

public static TOutput[,] ConvertAll<TInput, TOutput>(TInput[,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,])ConvertArray(array, converter);
}
public static TOutput[,,] ConvertAll<TInput, TOutput>(TInput[,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,,])ConvertArray(array, converter);
}
public static TOutput[,,,] ConvertAll<TInput, TOutput>(TInput[,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,,,])ConvertArray(array, converter);
}
public static TOutput[,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,,,,])ConvertArray(array, converter);
}
public static TOutput[,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,,,,,])ConvertArray(array, converter);
}
public static TOutput[,,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,,,,,,])ConvertArray(array, converter);
}
public static TOutput[,,,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,,,,,,,])ConvertArray(array, converter);
}
public static TOutput[,,,,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,,,,,,,,])ConvertArray(array, converter);
}
public static TOutput[,,,,,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
{
 return (TOutput[,,,,,,,,,])ConvertArray(array, converter);
}
static Array ConvertArray<T, TResult>(Array array, Converter<T, TResult> converter)
 where T : unmanaged
 where TResult : unmanaged
{
 if (array is null)
 {
 throw new ArgumentNullException(nameof(array));
 }
 if (converter is null)
 {
 throw new ArgumentNullException(nameof(converter));
 }
 long[] dimensions = new long[array.Rank];
 for (int i = 0; i < array.Rank; i++)
 dimensions[i] = array.GetLongLength(i);
 Array result = Array.CreateInstance(typeof(TResult), dimensions);
 TResult[] tmp = new TResult[1];
 int offset = 0;
 int itemSize = System.Runtime.InteropServices.Marshal.SizeOf(typeof(TResult));
 foreach (T item in array)
 {
 tmp[0] = converter(item);
 Buffer.BlockCopy(tmp, 0, result, offset * itemSize, itemSize);
 offset++;
 }
 return result;
}

All suggestions are welcome.

The summary information:

• Which question it is a follow-up to?

  ConvertAll Methods Implementation for Multidimensional Array in C#

• What changes has been made in the code since last question?

  Trying to perform higher dimensional overloadings and exception handling based on aepot's answer.

• Why a new review is being asked for?

  If there is any possible improvement or any other potential defect, please let me know.

• JimmyHu: @aepot Thank you for your comments. Already updated.
• aepot: As for me, looks fine now.

Answer 1

When I see that many recurrences like this then it is a good sign for me that this is a perfect place to introduce meta-programming via T4.

Step #1

Separate the overloads from the core logic:

using System;
namespace Sample.Core
{
 internal static class Converter
 {
 public static Array ConvertArray<T, TResult>(Array array, Converter<T, TResult> converter)
 where T : unmanaged
 where TResult : unmanaged
 {
 if (array is null)
 {
 throw new ArgumentNullException(nameof(array));
 }
 if (converter is null)
 {
 throw new ArgumentNullException(nameof(converter));
 }
 long[] dimensions = new long[array.Rank];
 for (int i = 0; i < array.Rank; i++)
 dimensions[i] = array.GetLongLength(i);
 Array result = Array.CreateInstance(typeof(TResult), dimensions);
 TResult[] tmp = new TResult[1];
 int offset = 0;
 int itemSize = System.Runtime.InteropServices.Marshal.SizeOf(typeof(TResult));
 foreach (T item in array)
 {
 tmp[0] = converter(item);
 Buffer.BlockCopy(tmp, 0, result, offset * itemSize, itemSize);
 offset++;
 }
 return result;
 }
 }
}

Step #2

Introduce a *.tt file with the following content:

<#@ template language="C#" #>
<#@ assembly name="System.Core" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
using System;
using static Sample.Core.Converter;
namespace Sample.Overloads
{
 public static class ArrayConverter
 {
<#
for(int i = 1; i < 10; i++)
{
var dimensions = new String(',', i);
#>
 public static TOutput[<#=dimensions#>] ConvertAll<TInput, TOutput>(TInput[<#=dimensions#>] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[<#=dimensions#>])ConvertArray(array, converter);
 }
<#
}
#>
 }
}

Step #3

Execute the tt file and examine the generated code:

using System;
using static Sample.Core.Converter;
namespace Sample.Overloads
{
 public static class ArrayConverter
 {
 public static TOutput[,] ConvertAll<TInput, TOutput>(TInput[,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,])ConvertArray(array, converter);
 }
 public static TOutput[,,] ConvertAll<TInput, TOutput>(TInput[,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,,])ConvertArray(array, converter);
 }
 public static TOutput[,,,] ConvertAll<TInput, TOutput>(TInput[,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,,,])ConvertArray(array, converter);
 }
 public static TOutput[,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,,,,])ConvertArray(array, converter);
 }
 public static TOutput[,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,,,,,])ConvertArray(array, converter);
 }
 public static TOutput[,,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,,,,,,])ConvertArray(array, converter);
 }
 public static TOutput[,,,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,,,,,,,])ConvertArray(array, converter);
 }
 public static TOutput[,,,,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,,,,,,,,])ConvertArray(array, converter);
 }
 public static TOutput[,,,,,,,,,] ConvertAll<TInput, TOutput>(TInput[,,,,,,,,,] array, Converter<TInput, TOutput> converter)
 where TInput : unmanaged
 where TOutput : unmanaged
 {
 return (TOutput[,,,,,,,,,])ConvertArray(array, converter);
 }
 }
}
```